Log in
Chemistry
0
answers
0
watching
155
views
19 Nov 2019

There are 10 unknown ID's. What compound are the Unknowns?

Clues:

1. Copper sulfate solutions are blue.

2. Acids react with sodium sulfide and release gas. Hydrogen sulfide smells like rotten eggs.

3. When a base is mixed with NH4Cl it will smell like ammonia (NH3).

4. Ammonia vapor will turn litimus paper blue when it is damp.

5. When silver nitrate is combined with compounds containing halogens (Br,Cl,I), white or yellow precipitates form.

6. BaCl2 reacts with H2 SO4 and CuSO4 and forks a white precipitate BaSO4.

7. When CuSO4 is mixed with KI it gives orange-yellow precipitate. No precipitate with NaBr.

8. When excess NaOH is added to BaCl2 white cloudy precipitate ((Ba(OH)) is formed.

9. HCl and AgNO3 react and produce AgCl( white precipitate).

10. AgCl forms white precipitate AgBr forms creamy or light yellow precipitate.

pH tests:

1. A. pH color is no change 4-6

2. B. pH color is blue 10-12

3. C. pH color is no change 4-6

4. D. pH color is red 1-2

5. E. pH color is no change 4-6

6. F. pH color is no change 4-6

7. G. pH color is red 2

8. H. pH color is no change 5

9. I. pH color is dark/ black 12

10. J. pH color is no change 3

When combined:

1. A+B=no rxn A+C=no rxn A+D=no rxn A+E=no rxn A+F=no rxn A+G=no rxn A+H=white, opaque A+I=no rxn A+J=yellow

2. B+C=no rxn B+D=white, precipitate formed B+E=white, cloudy B+F=no rxn B+G=no rxn, precipitate formed B+H=brown B+I=no rxn B+J=dark brown

3. C+D=no rxn C+E= no rxn C+F=no rxn C+G=no rxn C+H=white, cloudy opaque C+I=no rxn C+J=light blue

4. D+E=white, cloudy D+F=no rxn D+G=no rxn D+H=no rxn D+I=no rxn D+J=no rxn

5. E+F=no rxn E+G=no rxn E+H=white, cloudy similar to C+H E+I=no rxn, slight precipitate E+J=white

6. F+G=no rxn F+H=white, cloudy F+I=no rxn F+J=no rxn

7. G+H=white, cloudy G+I=no rxn G+J=no rxn

8. H+I=light brown H+J=no rxn

The Unknowns are AgNO3, BaCl2, CuSO4, HCl, H2SO4, KI, NaBr, NaOH, Na2S, NH4S

What is solution, explanation, and net ionic equation for the unknowns: A,B,C,D,E,F,G,H,I,J

Please match the compound with the unknown (letters a-j)

Watch
0
answers
0
watching
155
views

For unlimited access to Homework Help, a Homework+ subscription is required.

discord banner image
Join us on Discord
Chemistry Study Group
Join now

Related textbook solutions

Basic Chemistry
5 Edition,
Timberlake
ISBN: 9780134138046
Principles of Chemistry Molecular Approach
4th Edition,
Tro
ISBN: 9780134112831
Principles of Chemistry Molecular Approach
3rd Edition, 2014
Tro
ISBN: 9780321971944
Chemistry: Structure and Properties
2nd Edition,
Tro
ISBN: 9780134293936
Chemistry: A Molecular Approach
3rd Edition,
Tro
ISBN: 9780321809247
Chemistry: A Molecular Approach
5th Edition,
Tro
ISBN: 9780134874371
Principles of Chemistry: A Molecular Approach
4th Edition,
Tro
ISBN: 9780134895741
Chemistry: The Central Science
14th Edition, 2017
Brown
ISBN: 9780134414232

Related questions

To test for Ag+

1. add 2 drops 6M HCl to 1 mL of unknown sample. Centrifuge (3-4 minutes). Add 1 more drop of 6M HCl and centrifuge (if necessary). A precipitate will form; decant (pour off) solution to another test tube (save solution)

2. wash precipitate from step 1 with 1 or 2 mL of distilled water. Stir, centrifuge, and decant the liquid (can be discarded). Then add 1 mL of distilled water to precipitate and place the test tube in boiling water. Let the test tube boil, and stir occasionally. Centrifuge the hot test tube (solution) and then decant after centrifuging (save the decant solution). Save the precipitate.

3. Add 10 drops of 6M HNO3 to the precipitation from step 2 and stir it. Centrifuge and decant the solution (save it).

4. Add 6M HNO3 to the solution from step 3 until it is acidic toward litmus paper. If Ag+ is present in the acidic solution, a white precipitate of AgCl will form.

To test for Cu2+ and Sb3+

1. Add 15M NH3 to 1 mL of unknown sample until the solution is basic to litmus paper. A precipitate may form at this point due to the formation of insoluble oxychlorides of bismuth, tin, or antimony. Add 1 drop 6M HCL for each mL of solution. Verify the pH level by using methyl violet paper, the paper should turn blue-green. Adjustment may be necessary to achieve the blue-green color. Add HCl or NH3 until it is almost the same blue-green color.

2. Add 15-20 drops of 1M thioacetamide to solution and heat in boiling water for 5 minutes. Centrifuge and decant to another test tube (may contain Fe and Cr). Test solution for completeness of precipitation by adding 2 drops of thioacetamide and letting it sit for 1 minute. If precipitation forms, add a few more drops of thioacetamide solution and heat again. Combine the two batches of precipitate. Wash precipitate with 1 M NH4Cl solution, stir, and warm in bath water; centrifuge, and discard the wash solution.

3. To sulfide precipitate from step 2 add 15 drops of 6M KOH, 2mL of water, and 3 drops 1M thioacetamide. Heat solution in boiling water for 5 minutes and stir occasionally. Centrifuge and decant the solution. Wash any precipitate remaining twice with 5 drops of water and combine the washings with the solution. Tin and antimony will be present in the solution as complex ions, and copper and bismuth will remain as undissolved sulfide precipitate. Save precipitate for later.

4. Add 12 M HCL to the solution from step 3 until it is acidic toward litmus paper. When acidified, some tin and antimony will precipitate as orange sulfides. Add 5 drops of 1M thioacetamide and heat. Centrifuge and decant solution (this solution can be discarded)

5. Add 10-15 drops of 12M HCl to the precipitate from step 4 and heat for 5 minutes to dissolve precipitate. Continue heating until H2S is gone. Centrifuge out any insoluble sulfur residue.

6. Add 0.5 grams of oxalate acid and 2 mL of water to remainder of solution from step 5. Heat the solution, if necessary, to dissolve the oxalate acid. This reagent forms a stable complex ion with Sn4+. Add 10 drops of 1M thioacetamide and heat. Formation of an orange precipitate indicates the presence of antimony.

6. Add 30 drops of 6M HNO3 to remaining sulfide precipitate from step 3. Heat solution gently in boiling water to complete dissolution of the sulfides. Centrifuge the solution to remove sulfur and decant it into a small beaker. Place beaker on hot plate and evaporate the liquid to a volume of about one-half mL. DO NOT LET SAMPLE DRY OUT.

7. Add 15M NH3 dropwise to the solution obtained in step 8 until it is basic toward litmus paper. Add a few more drops. The formation of a deep blue solution indicates the presence of copper.

Testing for Fe3+ and Cr3+

1. [If a solution is being used from which group II cations have been precipitated, remove the H2S and excess acid by boiling the solution in a small beaker until a volume of about 1 mL. Remove any sulfur residue by centrifuging the solution.] [if a solution being used contains only group II ion, then use 1 mL of this solution.]

2. Add 3 drops of 3% H2O2 to 1 mL solution from step 1. Add 15 drops of 6M NaOH to solution to make it strongly alkaline (basic). Stir for 1 minute and boil to remove all excess H2O2. After H2O2 is decomposed, solution will ‘bumb’. If oxidation of chromium (II) has occurred, the solution will be yellow. If not, add 3 more drops of H2O2 and boil again. Centrifuge and decant. Save precipitate (contains Fe3+) and solution (contains Cr3+).

3. Acidify solution from step 2 by adding drops of 15 M HNO3(about 5 drops) and test with litmus paper. Add 6M NH3 drop by drop with mixing until solution is basic. This treatment will precipitate Al3+, will be gelatinous white. May appear yellow because of the presence of CrO42-. Centrifuge and decant the solution, it contains CrO42-. Add 1 M BaCl2 to solution from step 3 to precipitate yellow BaCrO4. If precipitate is slow to form, heat in boiling water. Centrifuge the solution and decant. Dissolve the precipitate in 3 drops of 6M HNO3; heat and stir. Add 4 drops of water and cool it down. Add 6 drops of diethyl ether followed by 1 drop of 3% H2O2. Shake gently, and allow layers to settle. A blue color in ether (top) later confirm test for chromium.

4. Add 8 drops of 15M HNO3 to precipitate from step 2. Heat until precipitate is dissolved. Allow to cool and add 10 drops of 1M NH4Cl and then add 15 M NH3 until solution is alkaline to litmus paper. This will precipitate iron as brown. Then add 4-5 drops of NH3 solution and stir. Centrifuge and decant solution (this solution may be discarded).

5. Dissolve the precipitate from step 5 by adding 10 drops of 6M HCl. Dilute with 2mL of distilled water and add 2 drops of 0.5M KSCN. A blood-red color indicates presence of Fe3+.

-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

I will be given 3 mL of an unknown sample and I will have 75 minutes to do a qualitative analysis for Ag, Cu, Sb, Fe, Cr.

I need help coming up with a flow chart based on the above steps so that it is makes this class assignment smoother since I will only be given 75 minutes to complete it.

Thank you!

I would like to get help to write an abstract about this experiments. Please and thank you.

This is the description from my organic chemistry lab.

Lab Observations and Data

We obtained 1.17g of cyclohexene oxide (clear liquid) and 3 mL of water into a 50 mL flask with a stir bar. When added a single drop of sulfuric acid, the clear liquid started to change to a very, very light yellow/brownish color. We obtained an ice bath on the side in case our mixture started to boil. After the solution stirred for about 25 minutes, we added sodium hydroxide. We inserted a pH paper and it turned a dark blue, meaning basic. Added another drop of sulfuric acid to make it a little less basic. Added the mixture to a separation funnel, shook it around and ended with separated layers. We separated the layers, thinking the bottom layer was the organic layer, when it was really the aqueous layer. So we ended up mixing the wrong layers back together. After some error, we isolated our new organic layer and added some drying agent. We then put that mixture with the drying agent, NaOH, into the rotovap. Our final product was a white powder and weighed 1.51 grams. We then set up a vacuum filtration while boiling water. We boiled our dried organic layer into the hexane. Added two drops of ethyl acetate to help the boiling process go faster. After vacuum filtering it, it weighed .394 grams. The melting point is 91 to 93 degrees Celsius. Our IR spectra matches the "trans" conformation. So for our TLC plate we observed blue dots to match the trans conformation.

The question is "calculate your percent yield" Which is actual yield/theoretical yield x 100. I just dont understand how I get those numbers.

Here is the lab manual description as well.

Procedure for the Preparation of 1,2-Cyclohexanediol Place a mixture of 1.18 g (0.012 mole) of cyclohexene oxide and 3 mL water into a 50 mL Erlenmeyer flask, equipped with a magnetic stir bar. To this mixture with vigorous stirring add one drop of 6 M sulfuric acid (33% H2SO4) Caution: After a short incubation time, the reaction mixture will become quite warm. This epoxide ring opening reaction is very exothermic. (Why?) If the reaction mixture begins to boil, place the flask in a bath of ice and water. Allow the reaction mixture to stir for the next 15 minutes and let it cool to room temperature. Afterwards, add a small amount of 10% sodium hydroxide drop-wise to neutralize the stirring solution. (No more than 3 or 4 drops of 10% NaOH should be necessary.) Place a drop of the reaction mixture on pH paper to check the pH. Extract the product from the reaction mixture into ethyl acetate or diethyl ether (2 x 15 mL). Dry the combined extracts over sodium sulfate. Decant the solution and remove the solvent to yield the crude product (~1 g). The product can be purified by recrystallization from a small amount (~ 5 mL) of hot toluene or hexanes. Collection of the purified product by suction filtration yields 1,2-cyclohexanediol. The cis isomer has a melting point of 97-101 °C whereas the trans isomer melts at 101-103 °C. Determine the product(s) or products the reaction. Include a percent yield calculation in your report along with the results of your TLC analysis

Weekly leaderboard

Home
Homework Help 3,900,000
Chemistry 830,000
Start filling in the gaps now
Log in